Reflex Epilepsy

Abstract

Reflex seizures (RS) are epileptic events that are objectively and consistently elicited in response to a specific afferent stimulus or by an activity of the patient. The specific stimulus can be a variety of heterogenous intrinsic or extrinsic factors, ranging from the simple to the complex, such as flashing lights or reading a book. These seizures can take a variety of forms, comprising either general or focal onset, with or without secondary generalization. Reflex epilepsies (RE) are classified as a specific syndrome in which all epileptic seizures are precipitated by sensory stimuli. The few designated RE include idiopathic photosensitive occipital lobe epilepsy, other visual sensitive epilepsies, primary reading epilepsy, and startle epilepsy. RS that occurs within other focal or generalized epilepsy syndromes that are associated with distinct spontaneous seizures are classified by the overarching seizure type. Most patients experience spontaneous seizures along with their provoked events. RS originate from stimulation of functional anatomic networks normally functioning for physiological activities, that overlap or coincide with regions of cortical hyperexcitability. Generalized RS typically occur within the setting of IGEs and should be considered as focal seizures with quick secondary generalization via cortico-cortical or cortico-reticular pathways. In aggregate, activation of a critical neuronal mass, supported and sustained by cortico-subcortical and thalamocortical pathways eventually result in a seizure. Treatment includes antiseizure medication, commonly valproate or levetiracetam, along with lifestyle modifications, and when amenable, surgical intervention. High clinical suspicion and careful history taking must be employed in all epilepsy patients to identify reflex triggers.

Towel induced reflex seizures

“…Reflex epilepsies are classified as extrinsic reflex epilepsies secondary to an extrinsic stimulus or intrinsic reflex epilepsies secondary to stimuli comprising higher brain function and specific activities carried out by the patient. Intrinsic reflex epilepsies include thinking epilepsy [6] . Our patient appears to fit both categories.…”

Startle Seizures and Diffuse Leukoencephalopathy After Resolution of Herpes Simplex Virus 1 Encephalitis in a Child

“…However, it had been described in patients with perinatal brain injury, traumatic brain injury, metabolic diseases, trisomy 21, and congenital brain malformations. 6 , 13 Interestingly, in the postencephalitic phase of the syndrome of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), startle seizures appear to be quite common. 3 AESD is a syndrome of acute encephalitis due to a viral trigger and is characterized by two phases of seizures and a characteristic appearance of widespread diffusion restriction of subcortical white matter with central sparing.…”

“…5 However, the underlying network in the generation of startle seizures remains to be clarified. 6 Reflex seizures refer to seizures that are constantly evoked by a specific stimulus, including the startle stimulus described herein. When occurring alone without other spontaneous seizures, this is referred to as reflex epilepsies.…”

Animal Models of Epilepsy: A Phenotype-oriented Review

“…Audiogenically vulnerable animals usually start with wild running and gradually evolve into a tonic-clonic phase [ 46 ]. Wistar audiogenic rats model is successfully established [ 51 ]. In this model, after exposure to repetitive sound stimuli with high intensity, Wistar audiogenic rats presented wild running, head ventral bending, back arching tonus, and limb hyperextension.…”